If you have 'developer's licence', the easiest way to do this is to write your own 'update' session that will read the BOM records from an ASCII file and create records in the BAAN table. [This assumes that Autocad is capable of at least creating an ascii output consisting of Parent Item, Component Item and Quantity per Parent.] The rest of the fields required by tibom010 table are easy to figure out by creating and observing a small BOM by hand. This is how I did this in my company and it has been running successfully for many years now.

There is one important pre-requisite: The Item Data (tiitm001) records (parent as well as components) must have been established in BAAN up front (this is done manually), because that is one of the validations that I do in my program.

At one of my project, we ported BOM for hundreds of finished goods during the last few weeks of implementation (just before they went live). We used API to create the hundreds of item data required as well as their BOMs. With simple commands in API, we could make sure that all the related tables (there are quite a few involved in this) are updated properly. Please look around the API discussion forum for more information

at S&T Slovenia we have developed a set of sessions specially designed to import ASCII data (exported from Autocad, ProfiDB or any other Windows application). Transaction logging and error reporting is also included. Sessions are based on AFS and are dynamically configured based on Import scheme. That means you can decide which fields you are going to insert in the Item or BOM table. They are much simpler to use than Exchange.
If you think this information is useful for you, feel free to contact me.